Siphonous seaweeds: a holobiont approach

Type:

Master Thesis subject (30 ECTS)

programme:

EMBC+

Siphonous green seaweeds (e.g. Caulerpa spp.) are among the morphologically most complex algae and also among the most notorious invasive species in many parts of the world. Their ecological success has repeatedly been linked to their association with bacteria. Indeed, recent studies revealed rich associated bacterial communities. However, little is known about the functional diversity of these communities as well as the principles underlying community assembly. To address how bacteria contribute to the ecological success of siphonous green algae and whether the competitive potential of invasive species may be at least partly shaped by associated microbes, we will analyse the functional diversity of epi- and endophytic bacterial communities associated with native and invasive species of Caulerpa. To address this objective you apply the following strategy: 1) Characterisation of bacterial communities across species (native and invasive) occurring in European waters based on 16S rDNA sequences. We will characterize bacterial communities from different parts of the plant (epi/endophytes, root-like structures and blades) based on 16S rDNA signatures (NGS-Illumina). The combined effect of host dependency, ecology and biogeography on the structure of the bacterial communities will be studied using a variation partitioning approach.
Practical work will involve: sampling natural populations (Turkey, the region in Europe boasting the highest European Caulerpa diversity); functional characterisation of the associated bacteria based on a metagenomic approach; testing of the functional response of bacterial communities to changing environmental conditions (lab experiments). We thereby focus on the ability of Caulerpa to take up nutrients from the substrate . The focus is on the invasive Caulerpa racemosa/cylindracea and C. prolifera, a native European species.